A. Technical Field
This invention relates to a unit-piece printing sheet used in printing business cards together and a process for producing the same.
B. Background Art
For conventional preparation of a desired number of cards having the same print and the same dimension, such as business cards and postcards, a special printing machine adapted to the dimensions of each card should be used in printing, and prints by the printing machine are very high in cost.
On the other hand, simultaneous printing of a large number of unit pieces as cards in one printing paper is more efficient than printing of each card. This particularly applies to cards or postcards having the same dimension and the same print.
It's more convenient if such unit-piece printing sheet can be applied not only to a special printer but also to a personal computer printer or a copier in a printing system where a printing plate is not required.
For this purpose, a constitution wherein like a label-forming laminate, a large number of releasable unit pieces are assembled and arranged on a mount is conceivable. In so doing, printing with a copier or a printer can also be made easy. However, when the label-forming unit pieces are released from the mount, a pressure-sensitive adhesive remains on the back of each unit piece, so that when the unit piece is to be immediately stuck on something, the unit piece can be used as it is, but the unit piece is not suitable for use as a card unit piece not intended to be stuck, for example a business card, a postcard, or an event ticket.
To solve the problem, there is a unit-piece printing sheet provided with perforations, comprising fine perforations arranged in a printing paper of large dimensions, and each square divided by the perforations is subjected to printing necessary for a business card, a postcard or an event tickets, and the desired cards are obtained by tearing the sheet into pieces along the perforations. In this constitution, however, an notched cut caused by the perforations is observed on the periphery of each unit piece.
Accordingly, a printing laminate comprising a printing base material laminated via an adhesive layer on a supporting base material, wherein the printing base material comprises unit pieces in aggregate formed not via perforations but via slits was conceivable. This is because given slits, the cut portion as the periphery of each unit piece can be beautifully finished. This laminate is constituted such that each unit piece is made easily releasable by applying a release agent onto the back of the unit piece, but with this constitution given, a sense of incongruity, that is, a sense of extreme smoothness, remains on the back of the released unit piece. In addition, there is the problem that the surface of the supporting base material layer after released from the unit piece is sticky.
To solve this problem, a printing laminate comprising a propylene type resin or another thermoplastic resin layer formed on a supporting base material, in place of an adhesive layer formed on a supporting base material, has been proposed (JP-A 5-318672, JP-A 8-286414, JP-A 9-158087). A thermoplastic resin such as polypropylene resin shows bonding properties (pseudo-adhesion) but is hardly released, and curling of the released unit is inevitable. Another problem is that its release becomes harder as time passes.
To solve this problem, the present inventors invented a unit-piece printing sheet showing excellent pseudo-adhesion, which while facilitating occurrence of pseudo-adhesion between a printing base material and a thermoplastic resin layer, also facilitates occurrence of strong adhesion between a supporting base material and the thermoplastic resin layer, and they filed an application therefor (JP-A 2002-019206). That is, this prior art relates to a printing laminate comprising a printing base material layer laminated on a supporting base material via a thermoplastic resin layer, wherein the printing base material layer is a layer provided with unit pieces in aggregate arranged via slits, and the thermoplastic resin layer is a layer made of linear low-density polyethylene resin, whereby the bonding strength between the printing base material layer and the thermoplastic resin layer is made lower than the bonding strength between the supporting base material layer and the thermoplastic resin layer, and each unit piece is subject to pseudo-adhesion to the supporting base material layer and is easily released therefrom.